1. Field of the Invention
The present disclosure generally relates to a system for processing image data using one or more image processing units, and more particularly, to a system that can process special image data such as paper currency or stock certificates, which by their nature pose special problems of copying, printing, display, and storage.
2. Description of the Background Art
For obvious reasons, certain documents, such as paper currency and stock certificates, must by nature be made difficult to counterfeit by copying.
Accordingly, multi-functional image forming apparatuses, such as digital color multi-functional peripherals, are often equipped with a copy-prohibition function that prevents proper copying even when certain types of documents are scanned, so that the copied document is not used for illicit purposes.
Specifically, when the image forming apparatus equipped with such a copy-prohibit function scans the document, the image forming apparatus can detect that the document is a copy-prohibited document (hereinafter also sometimes referred to as a “special document”) and processes the document differently from an ordinary document, for example by blotting out the entire image with a pattern if the scanned document is a special document. As a result, the copy of the special document that is output is not a normal, usable image. JP-2006-287707-A, for example, discloses such a method.
However, this conventional approach may have drawbacks. For example, even if scanned image data does not include a special document, the scanned image data cannot be output to an external environment of the image processing apparatus (e.g., an external device connected to the image processing apparatus) until it is determined that the scanned image data does not include a special document. Accordingly, the scanned image data may need to be retained temporarily until the special document determination is completed, by which a time for completing image forming such as copying may become undesirably longer. If a detection processing speed for special document becomes slower than an image inputting speed or image scanning speed, a throughput of image processing system as a whole declines due to a delay at the detection processing.
To return to JP-2006-287707-A as an illustration of the above-described drawback, this application discloses an image processing apparatus that includes an image output unit for conducting an image treatment process, and a memory unit for conducting a specific image treatment process to prevent a storage and output of copy-prohibited special document image data (e.g., paper currency, stock certificates) while maintaining a performance of first copy time (e.g., time to copy image).
In such an image processing apparatus, if a special document is detected, the image output unit may conduct a special image processing, which fills an entire image with a given pattern using image data of raster image. In such a configuration, the special image processing may be conducted after checking all input image data. Accordingly, it can be determined for the first time that special document is included in the input image data only after the all input image data is checked.
Therefore, until it is determined whether a special document is included or not in the input image data, no image data can be output (e.g., transfer) outside the image processing apparatus. In other words, a detection result for input image data, which indicates whether or not the image data includes a special document, is required before outputting image data from the image processing apparatus. Thus, for example, if a special document is included only at a last part of input image data, a longer time is required to issue such detection result.
Therefore, if an image processing system is comprised of an image processing apparatus and an output unit (e.g., printer or the like), a data transmission time from the image processing apparatus to the printer may become undesirably longer because even a part of input image data cannot be output from the image processing apparatus until all the input image data is checked.
A detailed description is now given of the exact steps in conventional processing described above with reference to FIG. 1.
FIG. 1 shows a block diagram of a conventional image processing system having a special document determination function. The image processing system for inputting and outputting image data includes an image input unit 51, an image processing unit 52, an image storage unit 53, a data output unit 54, a special document determination unit 55, and an image treatment unit 56, for example.
The image input unit 51 may be a document scanner provided for a copier, for example, in which document data is read and converted into digital data, and then input to an image processing apparatus. The input image data is then transmitted to the image processing unit 52, which conducts normal image processing, and in parallel, the input image data is transmitted to the special document determination unit 55. The special document determination unit 55 detects whether the input image data includes a copy-prohibited document (e.g., paper currency). The special document determination unit 55 is provided independently from the image processing unit 52.
After the image processing unit 52 conducts an image processing to the input image data, and the image data is sequentially stored to the image storage unit 53. While the image data is being stored to the image storage unit 53, the special document determination unit 55 continuously conducts a detection process for the input image data to check whether the input image data includes a special document. When one page of the input image data is checked, the special document determination unit 55 transmits the determination result to the image treatment unit 56. If the determination result is “special document is included,” the image treatment unit 56 conducts an image treatment process to the image data for one page stored in the image storage unit 53. For example, a given pattern (e.g., dots-printed pattern) may be filled on a whole-face of printed image.
If the determination result of the special document determination unit 55 is “special document is not included,” the image treatment unit 56 does not conduct an image treatment to the image data.
Then, the data output unit 54 outputs image data for one page stored in the image storage unit 53 to an external unit (e.g., printer or the like). If a copier is used as an image processing apparatus, the data output unit 54 may be an image printing unit, which may prepare data for image printing.
However, in such a conventional image processing apparatus, the image storage unit 53 needs to retain image data that needs to be checked by the above-described determination process until the special document determination unit 55 can complete a determination process and issues a determination result for input image data. Typically, input image data for one page is checked as one image data in the above-described determination process. Accordingly, until a whole of input image data is completely checked, a determination result cannot be issued. Such process may be required to prevent outputting a part or whole of a copy-prohibited document externally (e.g., as printed sheet, as electronic data).
Accordingly, if the special document determination unit 55 may need to conduct the above-described determination process for a given time duration that is longer than a processing time required by the image processing unit 52, a total time for completing a whole process (i.e., a time from inputting image data input to outputting the image data such as printing) may undesirably become longer because of the above-described determination process that determines whether a special document is included.